09/03/2013

Acid Rain - Causes, History and Effects

What is acid rain?

The effects of acid rain

Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are  produced. The smoke that comes from a fire or the fumes that come out of a car exhaust don't just contain the sooty grey particles that you can see - they also contains lots of invisible gases that can be even more harmful to our environment.

Power stations, factories and cars all burn fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen oxides and sulphur dioxide) react with the tiny droplets of water in clouds to form sulphuric and nitric acids. The rain from these clouds then falls as very weak acid - which is why it is known as "acid rain".  The release of sulphur dioxide can also occur naturally when a volcano erupts.

Acid rain was considered a major problem in the 1980s and while steps to reduce sulphur emissions have been succesful we are still feeling the effects today, and there is still work to be done.

Related Articles:
What is acid rain? 
Where is it coming from? 
How acidic is it? 
The effects of acid rain 
Forests 
Lakes and rivers 
Buildings 
What has been done? 
What about nitrogen? 
Restoring the damage 
What can we do to help?

read more

The Causes, History, and Effects of Acid Rain


Acid rain is rain consisting of water droplets that are unusually acidic because of atmospheric pollution - most notably the excessive amounts of sulfur and nitrogen released by cars and industrial processes. Acid rain is also called acid deposition because this term includes other forms of acidic precipitation such as snow.

Acidic deposition occurs in two ways: wet and dry. Wet deposition is any form of precipitation that removes acids from the atmosphere and deposits them on the Earth’s surface. Dry deposition polluting particles and gases stick to the ground via dust and smoke in the absence of precipitation. This form of deposition is dangerous however because precipitation can eventually wash pollutants into streams, lakes, and rivers.

Acidity itself is determined based on the pH level of the water droplets. PH is the scale measuring the amount of acid in the water and liquid. The pH scale ranges from 0 to 14 with lower pH being more acidic while a high pH is alkaline; seven is neutral. Normal rain water is slightly acidic and has a pH range of 5.3-6.0. Acid deposition is anything below that scale. It is also important to note that the pH scale is logarithmic and each whole number on the scale represents a 10-fold change

Related Articles:

read more 

Acid rain


Processes involved in acid deposition (note that only SO2 and NOx play a significant role in acid rain

Trees killed by acid rain 

Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970s to reduce the release of sulfur dioxide into the  atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes and sulfur dioxide is produced by volcanic eruptions. The chemicals in acid rain can cause paint to peel, corrosion of steel structures such as bridges, and erosion of stone statues.

"Acid rain" is a popular term referring to the deposition of wet (rain, snow, sleet, fog, cloudwater, and dew) and dry (acidifying particles and gases) acidic components. Distilled water, once carbon dioxide is removed, has a neutral pH of 7. Liquids with a pH less than 7 are  acidic, and those with a pH greater than 7 are alkaline. “Clean” or unpolluted rain has an acidic pH, but usually no lower than 5.7, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid. However, unpolluted rain can also contain other chemicals which affect its pH. A common example is nitric acid produced by electric discharge in the atmosphere such as lightning.

read more

Acid rain

The effects of acid rain on forests in the Jizera Mountains, Czech Republic. Source: Wikimedia Commons
The effects of acid rain on forests in the Jizera Mountains, Czech Republic. Source: Wikimedia Common
Lake acidification begins with the deposition of the byproducts acid precipitation (SO<sub>4</sub> and H ions) in terrestrial areas located adjacent to the water body. Hydrologic processes then move these chemicals through soil and bedrock where they can react with limestone and aluminum-containing silicate minerals. After these chemical reactions, the leachate continues to travel until it reaches the lake. The acidity of the leachate entering lake is controlled by the chemical composition of the effected lake's surrounding soil and bedrock. If the soil and bedrock is rich in limestone the acidity of the infiltrate can be reduced by the buffering action of calcium and magnesium compounds. Toxic aluminum (and some other toxic heavy metals) can leach into the lake if the soil and bedrock is rich in aluminum-rich silicate minerals. (Source: <a href='http://www.physicalgeography.net/' _fcksavedurl='http://www.physicalgeography.net/' class='external text' title='http://www.physicalgeography.net/' rel='nofollow'>PhysicalGeography.net</a>)
Effects on surface water quality

Acid rain is a popular term for the atmospheric deposition of acidified rain, snow, sleet, hail, acidifying gases and particles, as well as acidified fog and cloud water. The increased acidity of these depositions, primarily from the strong acids, sulfuric and nitric, is generated as a by-product of the combustion of fossil fuels containing sulfur or nitrogen, especially  electrical utilities (power plants.)

The heating of homes, electricity production, and driving vehicles all rely primarily on fossil fuel energy. When fossil fuels are combusted, acid-forming nitrogen and sulfur oxides are released to the atmosphere. These compounds are transformed chemically in the atmosphere, often traveling thousands of kilometers from their original source, and then fall out on land and water surfaces as acid rain.

As a result, pollutants from power plants in New Jersey, Ohio or Michigan can impact forests, rivers or lakes in less developed parts of New Hampshire or Maine.

read more

Air Quality, Air Pollution and Climate Change

acid rain

The term ‘acid rain’ means any form of precipitation like rain, fog, snow, or hail that contains harmful substances such as nitrogen and sulfur oxides. The major human sources do come from the industry, transportation, and a variety of power plants. Strictly speaking these industrial amounts of nitrogen, sulfur oxides and general pollutants from the air cause a drastic increase of the acidity of the precipitation and do also harm plants, humans, and buildings. 

In order to save the climate and to protect the general air quality the Air Pollution & Climate Secretariat, formerly known as the Swedish NGO Secretariat in Acid Rain, tries to promote awareness of the variety of problems being associated with air pollution. Strictly speaking the Air Pollution & Climate Secretariat is a joint venture between five Swedish environmental organizations.

This secretariat operates with the chief purpose to achieve the required reduction of the emission of air and industrial pollutants, including greenhouse gases. Consequently those emissions should be brought down to a level that our environment and nature are able to tolerate without suffering any damage regarding plants, buildings, and humans.

read more

What effect does acid rain have on sea life

There are many forms of acid rain that are seen around the world. In parts of the world where there is wet weather, there is acid rain, acid snow, and acid fog. In parts of the world where there is dry weather, there is acid gas and acid dust. Of all the lakes and streams in the world are normally slightly acidic. Heavy rainstorms or melting snow can cause the acidity in lakes and in streams to increase.

Acid rain is very harmful to the environment. Acid rain damages everything over a period of time because it makes the living things in the environment die. Acid rain affects the life in the water as well as the life on land. It is almost worse in water than on land because the fish that are in the water need the water to breathe. When the water gets polluted, then the fish get sick and end up dying.

All rainwater contains some level of acidity. Acidity is measured by pH, which stands for potential of hydrogen. The pH scale measures the amount of acid in a substance. PH is measured on a scale from 0-14, with 7 being neutral. The lower the number is on the pH scale, the more acidic that substance is. Normal rainwater has a pH of 5.6. When the pH level of rainwater goes below 5.6, it is considered acid rain.

read more

Acid rain

The term acid rain refers to what scientists call acid deposition.  It is caused by airborne acidic pollutants and has highly destructive results.

Scientists first discovered acid rain in 1852, when the English chemist Robert Agnus invented the term.  From then until now, acid rain has been an issue of intense debate among scientists and policy makers.
Acid rain, one of the most important environmental problems of all, cannot be seen.  The invisible gases that cause acid rain usually come from automobiles or coal-burning power plants.

Acid rain moves easily, affecting locations far beyond those that let out the pollution.  As a result, this global pollution issue causes great debates between countries that fight over polluting each other's environments.

read more

What is Acid Rain?

Flow chart showing dry and wet deposition processes. If you have difficulty viewing this graphic, or need additional information, contact Cindy Walke, Web Manager, at 202-343-9194.

"Acid rain" is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) resulting from fossil fuel combustion.

In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels, like coal.  Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds.

The result is a mild solution of sulfuric acid and nitric acid. When sulfur dioxide and nitrogen oxides are released from power plants and other sources, prevailing winds blow these compounds across state and national borders, sometimes over hundreds of miles

read more

Formation of Acid rain


Tonnes of dead fish spotted at Lim Chu Kang, Sungei Buloh, due to lack of oxygen in waters

Dead fish spotted at Lim Chu Kang beach. (Photo by Ria Tan)
Yahoo! Newsroom - Dead fish spotted at Lim Chu Kang beach. (Photo by Ria Tan)

Tonnes of fish from four farms at the Lim Chu Kang area have died due to the lack of oxygen in the water, said the Agri-Food & Veterinary Authority (AVA).

Some of the close to 90,000kg of dead fish, mainly mullet and milkfish, have also been sighted at Sungei Buloh Wetland Reserve (SBWR).


According to a statement by the AVA, the lack of oxygen is due to the recent hot and dry weather conditions with little rainfall.

read more

Haze doesn’t change safety of Singapore’s water: Vivian Balakrishnan

Environment Minister Vivian Balakrishnan helps a public waste disposal worker put on an N95 mask correctly, to ensure he is taking adequate precautions should the haze worsen. (Yahoo! photo)

Haze has had "absolutely no impact" on the quality of water for public consumption, said Minister for the Environment and Water Resources Vivian Balakrishnan.

Speaking on Wednesday morning at the sidelines of a visit to Chestnut Waterworks, a processing plant that controls one-third of the nation's water supply, Balakrishnan said the system of filtration and water purification for Singapore's tap water has built-in redundancies, and that the water flowing through the country's taps is as clean as it was pre-haze season.

"PUB has been monitoring water quality quite obsessively over the past couple of weeks and the first point to note is that there has been absolutely no impact on the quality of our water, both in terms of the raw water and the treated water we are putting out to the public," he said. 

read more

Singapore hailstorm is not toxic according to NEA

Hailstones. <a href="http://en.wikipedia.org/wiki/File:Hailstones.jpg" target="_blank">Bdahl/Wikipedia</a>

A hailstorm that hit certain cities in western Singapore Tuesday is not toxic, the National Environment Agency (NEA) said in a conference.

According to the NEA the hail is caused by supercooled water drops that freeze upon contacting particles in the air during thunderstorms. The agency added that pollutants known as PM2.5 and PM10 are only hazardous when inhaled.

The National Environment Agency said in a statement that the hailstorm that hit western Singapore Tuesday was not toxic.

read more

NEA: Hail not related to cloud seeding, rain is not toxic

Broken-off branches in carpark are seen in Bukit Batok.&nbsp;Residents in the western end of Singapore are reporting incidences of hail.&nbsp;-- ST PHOTO: JOYCE FANG
Broken-off branches in carpark are seen in Bukit Batok. Residents in the western end of Singapore are reporting incidences of hail. -- ST PHOTO: JOYCE FANG

The National Environment Agency (NEA) has confirmed that the hail that some residnets, particularly those living in the western parts of Singapore experienced, is not caused by the cloud seeding in Indonesia. 

It said in a briefing on Tuesday evening, that clouds do not travel that far and the clouds would be going in the wrong direction if it was related as the wind is currently blowing the haze away from Singapore. 

Asked if the hail was related to the haze, NEA would only say that it was a possibility but could not give a confirmation. It added that the heavy downpour on Tuesday afternoon was not toxic.

read more

Singapore Hailstorm Not Toxic, Agency Says



A Singapore hailstorm on Tuesday helped clear up the haze clouding the city-state for the past few weeks. 

The hailstorm affected several parts of Singapore, and a National Environment Agency spokesman assured the public–telling Yahoo News and other media–that it was not toxic.

The Singapore environment agency denied claims that cloud-seeding caused the hailstorm, reported the Asia One website.

read more